AMD SC3200 manual Super I/O Module, Clock, Timers, and Reset Logic, Power-On Reset, System Reset

Architecture Overview 32581C

•Sub-ISA: See Section 3.4.7 "Sub-ISA Interface Signals" on page 57, Section 6.2.5 "Sub-ISA Bus Interface" on page 145, and Section 4.2 "Multiplexing, Interrupt Selec- tion, and Base Address Registers" on page 70

•GPIO: See Section 3.4.16 "GPIO Interface Signals" on page 65.

•More detailed information about each of these interfaces is provided in Section 6.2 "Module Architecture" on page 140.

•Super/IO Block Interfaces: See Section 4.2 "Multi- plexing, Interrupt Selection, and Base Address Regis- ters" on page 70, Section 3.4.5 "ACCESS.bus Interface Signals" on page 52, Section 3.4.13 "Fast Infrared (IR) Port Interface Signals" on page 62, and Section 3.4.12 "Parallel Port Interface Signals" on page 61.

The Core Logic module interface to the GX1 module con- sists of seven miscellaneous connections, the PCI bus interface signals, plus the display controller connections. Note that the PC/AT legacy signals NMI, WM_RST, and A20M are all virtual functions executed in SMM (System Management Mode) by the BIOS.

•PSERIAL is a one-way serial bus from the GX1 to the Core Logic module used to communicate power- management states and VSYNC information for VGA emulation.

•IRQ13 is an input from the GX1 module indicating that a floating point error was detected and that INTR should be asserted.

•INTR is the level output from the integrated 8259A PICs and is asserted if an unmasked interrupt request (IRQn) is sampled active.

•SMI# is a level-sensitive interrupt to the GX1 module that can be configured to assert on a number of different system events. After an SMI# assertion, SMM is entered and program execution begins at the base of the SMM address space. Once asserted, SMI# remains active until the SMI source is cleared.

•SUSP# and SUSPA# are handshake signals for imple- menting CPU Clock Stop and clock throttling.

•CPU_RST resets the CPU and is asserted for approxi- mately 100 µs after the negation of POR#.

•PCI bus interface signals.

2.4Super I/O Module

The SuperI/O (SIO) module is a PC98 and ACPI compliant SIO that offers a single-cell solution to the most commonly used ISA peripherals.

The SIO module incorporates: two Serial Ports, an Infrared Communication Port that supports FIR, MIR, HP-SIR, Sharp-IR, and Consumer Electronics-IR, a full IEEE 1284 Parallel Port, two ACCESS.bus Interface (ACB) ports, Sys- tem Wakeup Control (SWC), and a Real-Time Clock (RTC) that provides RTC timekeeping.

2.5Clock, Timers, and Reset Logic

In addition to the four main modules (i.e., GX1, Core Logic, Video Processor and SIO) that make up the SC3200, the following blocks of logic have also been integrated into the SC3200:

•Clock Generators as described in Section 4.5 "Clock Generators and PLLs" on page 81.

•Configuration Registers as described in Section 4.2 "Multiplexing, Interrupt Selection, and Base Address Registers" on page 70.

•A WATCHDOG timer as described in Section 4.3 "WATCHDOG" on page 77.

•A High-Resolution timer as described in Section 4.4 "High-Resolution Timer" on page 79.

2.5.1Reset Logic

This section provides a description of the reset flow of the SC3200.

2.5.1.1Power-On Reset

Power-on reset is triggered by assertion of the POR# sig- nal. Upon power-on reset, the following things happen:

•Strap balls are sampled.

•PLL4, PLL5, and PLL6 are reset, disabling their output. When the POR# signal is negated, the clocks lock and then each PLL outputs its clock. PLL6 is the last clock generator to output a clock. See Section 4.5 "Clock Generators and PLLs" on page 81.

•Certain WATCHDOG and High-Resolution Timer register bits are cleared.

2.5.1.2System Reset

System reset causes signal PCIRST# to be issued, thus triggering a reset of all PCI and LPC agents. A system reset is triggered by any of the following events:

•Power-on, as indicated by POR# signal assertion.

•A WATCHDOG reset event (see Section 4.3.2 "WATCHDOG Registers" on page 78).

•Software initiated system reset.

AMD Geode™ SC3200 Processor Data Book 23